Electrochemical synthesis of polythiophenes

Electrochemical synthetic methods were also attempted around this time, yet this approach was limited due to solubility issues of the polymer. Electrochemical synthesis of polythiophene was typically performed on metal substrates, the most common being platinum, silver, iron and copper electrodes... 

Electrochemical synthesis of polythiophene was first reported in 1981 [73,74] with material which displayed a conductivity in the range 10 to 10 S cm . Other workers [75-77] polymerized thiophene with a variety of supporting electrolytes to produce thin films from acetonitrile solutions. Similar results were achieved by Kaneto et al. [78-80] using anhydrous solvents (acetonitrile and benzonitrile). 

Since the first studies rqjorting in 1982 the electrochemical synthesis of polythiophene [116], much research has been devoted to the optimization of this oxidative polymerization. Aldiough a-a coupling of... 

Electrochemical synthesis of electroconducting polymers such as polyarene [28— 31], polypyrrole [32-34], polythiophene [35], and polyaniline [36, 37] has been carried out in moisture sensitive chloroaluminate ionic liquids. However, the polymer hlms are decomposed rapidly by the corrosive products like HCl generated by hydrolysis of the ionic liquids. In addition the treatment of the chloroalminate ionic liquids requires a special equipment such as glove box. 

As in the cases of pyrrole and aniline polymers, both chemical and electrochemical procedures have been employed in the synthesis of polythiophene (PTH) and its derivatives. The thiophene polymers exhibit remarkable stability in air and water [119], The alkyl-substituted derivatives also exhibit a high degree of processability [120,121]. PTH has also been synthesized from bithiophane (the dimer) or terthiophene (the trimer). The resulting poly(2,2 -bithiophene) (PbTH) and polyterthiophene (PtTH) are more ordered than PTH and appear to have the same basic structure as the starting monomer [117,122],... 

Synthesis of polythiophene is possible by electrochemical and chemical polymerization techniques. The technique used in electrochemical synthesis is similar to that used for polypyrrole. As the starting materials, dimer [60-62], trimer [61, 63] and tetramer [61] can be used. 

Atobe, M., Ohsuka, H. and Fuchigami, T. (2004) Electrochemical synthesis of polypyrrole and polythiophene in supercritical trifluoromethane. Chemistry Letters, 33, 618-619. 

Among all the methods of synthesis to produce polypyrrole, the electrochemical procedure is, with difference, the most useful to obtain polypyrroles having high conductivities. The general details of electrochemical synthesis of polypyrrole are similar to other conducting polymers such as polythiophene or polyfurane. The flow of an anodic current in a simple electrochemical cell, through a solution containing a... 

Related Polymer Systems and Synthetic Methods. Figure 12A shows a hypothetical synthesis of poly (p-phenylene methide) (PPM) from polybenzyl by redox-induced elimination. In principle, it should be possible to accomplish this experimentally under similar chemical and electrochemical redox conditions as those used here for the related polythiophenes. The electronic properties of PPM have recently been theoretically calculated by Boudreaux et al (16), including bandgap (1.17 eV) bandwidth (0.44 eV) ionization potential (4.2 eV) electron affinity (3.03 eV) oxidation potential (-0.20 vs SCE) reduction potential (-1.37 eV vs SCE). PPM has recently been synthesized and doped to a semiconductor (24). 

Synthesis and Electrochemical Properties of a Polythiophene—Viologen Polymer... 

In this article we report the synthesis and electrochemical properties of the polymer derived from oxidation of X, poly(I), and the characteristics of a microelectrochemical transistor based on the polymer. Poly(I), which is formed by electrochemical oxidation of X, Equation 1, consists of a conducting polymer backbone, polythiophene. 

Thiophene, pyrrole and their derivatives, in contrast to benzene, are easily oxidized electrochemically in common solvents and this has been a favourite route for their polymerization, because it allows in situ formation of thin films on electrode surfaces. Structure control in electrochemical polymerization is limited and the method is not well suited for preparing substantial amounts of polymer, so that there has been interest in chemical routes as an alternative. Most of the methods described above for synthesis of poly(p-phenylene) have been applied to synthesise polypyrrole and polythiophene, with varying success. 

Summaries on the synthesis, properties, and uses of polythiophenes are included in two general reviews on poly thiophenes [259,260]. A synopsis of important aspects of polythiophenes are also included in several reviews on various aspects of conducting polymers [221-226], Cation radicals are the propagating species in both electrochemical and chemical oxidative polymerizations of thiophene and its derivatives. The polymer obtained by this method is linked primarily by a,a-linkages. However, other types of linkages (a,f3 and /3,/3) are present in varying amounts (Fig. 59). Substituted thiophene derivatives can couple in a head-to-tail or head-to-head manner. 

The preparation of polypyrrole, polythiophene, polyaniline, and related conducting polymers demonstrates principles of electrochemical synthesis that are more widely applicable, and it is instructive to examine these in detail. 

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